Can I process cards if I’m outside the USA?

If you’re a U.S. merchant traveling abroad, the main thing to worry
about is access to Wi-Fi or cellular data roaming charges. You should
be able to accept most Visa/MasterCard cards from abroad, but some
cards are regional and will not be accepted. Your charges will be in
USD, and currency conversion will be performed by the customer’s bank.
It’s quite similar to if your foreign customers had visited the United
States and used their credit card while visiting.